The present invention relates to a device for inputting a rotational operation quantity, and particularly to a mass-produced input device suitable for use in small electrical appliances and an operating device using this input device.
Small electrical appliances with a built-in microprocessor, such as cellular telephones, digital cameras, electronic game machines, or PDA devices, have spread remarkably, and, recently, demand has risen for various input devices to be built into these electrical appliances or into their peripheral devices. Generally, a device capable of indicating an operation quantity in an X-axis direction and an operation quantity in a Y-axis direction in an XY two-dimensional rectangular coordinate system or a device capable of performing click input in addition to the indication of the operation quantities is widely used as an input device for these electrical appliances. If the operation quantities in the X-axis and Y-axis directions can be indicated, it is possible to perform the operation of moving a cursor or a pointer on a display screen to an arbitrary position and perform the operation of selecting a predetermined item from a menu panel.
A device having a built-in two-dimensional force sensor is widely used as an input device for performing such an operation. The two-dimensional force sensor can divide the operation performed by an operator's thumb or finger into an operation quantity in the X-axis direction and an operation quantity in the Y-axis direction, and can recognize the operation quantities in the directions independently of each other. Preferably, a two-dimensional force sensor to be built into a small electrical appliance or its peripheral device is small and is suitable for mass production. In actual use, the two-dimensional force sensor employs various detecting elements, such as a capacitance element, piezoresistance element, and piezoelectric element.
If an input device for use in an electrical appliance has the function of inputting an operation quantity in the X-axis direction and an operation quantity in the Y-axis direction in the XY two-dimensional rectangular coordinate system and the function of performing the click input as mentioned above, it will become possible to execute almost all general application software programs on this electrical appliance. However, there are not a few application software programs that can be executed more flexibly if a rotational operation quantity can be input. For example, in software that reproduces sound or moving image, if the manner of being instructed by a rotational operation is employed when sound volume or forwarding/rewinding is adjusted, it will become possible to provide more intuitive instructions and obtain excellent operability.
An input device employing a rotary variable resistor or a variable capacitor has been conventionally used to input such a rotational operation quantity. However, such an input device has difficulty in being reduced in size and is not necessarily suitable to be built into a small electrical appliance, such as a cellular telephone, digital camera, electronic game machine, or PDA device. Additionally, these small electrical appliances each have a built-in input device employing the aforementioned two-dimensional force sensor in order to move a cursor or a pointer, and therefore it is inefficient to build still another input device thereinto in order to input a rotational operation quantity.